Ingot mold and ingot



Patented May 20, 1941 i a I UNITED STATES PATENT OFFICE Emil Gathmann,Baltimore, Md., assignor to Gathmann Research Incorporated, Catonsville,Md., a corporation of Maryland Application February 1, 1941, Serial No.377,030

4'Claims.

This invention relates to ingot molds and ingots and more particularlyto big-end-up molds and ingots having necked-in portions at their lowerends as shown, for example, in my prior United States Patents 1,188,751of June 27, 1916; 1,570,473 of January 19, ,1926; 1,573,486 of February16, 1926; 1,660,037 of February 21, 1928; and 2,047,098'of July 7, 1936,and others well known in the art.

The bottom contour in a general way common to the molds disclosed in theaforementioned patents has been employed in the production of manymillions of tons of ingots which, in addition to the attribute ofsoundness of a high percentage of the ingot metal, have had theadvantage of being easily handled in rolling, particularly durin theinitial roll passes.

In the production of high quality steels, the industry has accepted asnecessary the cropping of varying amounts of metals at both ends ofingots in order to remove unsound metal characteristicallyv present inthe ingot end portions. An object of the present invention is to reducethe, unsoundness of the metal at the bottom ends of ingots of the classreferred to above, or to confine the unsoundness to a zone nearer theingot bottom, the concave arcs having radii at least twice as long astheradii of the arcs defining the convex portions of the bottom contour.

Illustrative embodiments of the invention are shown in the accompanyingdrawing, in which:

- and Figure 4 is va vertical sectional view of an ingot embodying theinvention.

A mold M shown as an example of the various kinds of molds in which theinvention may be .embodied is formed of suitable heat absorbing.material'such as cast iron and is provided with the usual lifting lugsL. The mold is formed with a big-end-up chamber which is fluted orcorrugated in horizontal cross section as shownin Figure 2, but it willbe understood that the invention may be embodied in molds having othercross sectional contours, such for example as the cross sectionalcontours disclosed in the extreme bottom end of the ingot thanheretofore has been possible, so as to permit removal of any unsoundmetal with a minimum croppage loss.

It is generally consideredthat the solidification of ingot metalprogresses from the mold walls into the body of the ingot along lines atright angles to the mold walls. Thus, in the solidification extendinginto the ingot from a perfectly flat mold bottom, or a mold bottom alarge portion of which is concave, the formation of the dendriticcrystals grows upwardly and inwardly to such a great extent as tointerfere with the lines of freezing from the relatively more verticalmold sidewalls. Such interference apparently is the cause of theformation of-the porous ingot structure often found in zones above thebottom of the ingot as much as five or eight per cent of the ingotheight. I have found that. these porous metal zones may be largelyreduced and confined nearer the extreme bottom. of the ingot byproviding a necked-in ingot bottom contour the dominant portion of whichis concave in vertical section and which is connected to the ingot sidesurfaces by a convex portion of considerably lesser extent. The bestresults have been obtained with ingots whose concave bottom portions aredefined by arcs at least twice as long as the arcs defining theconvexportions of the prior patents previously referred to herein.- Theseveral fluted portions or corrugations merge with each other to form aside wall I extending continuously around the ingoteforming chamber;

The bottom of the mold is formed with a centrally disposed bottomopening 2.

The side wall I merges at its bottom with a necked-in wall portion Nterminating at the bottom opening 2. In accordance with the inventionthe necked-in portion comprises a conlong as thevradius R this relationhaving been found best in practice for molds of the size disclosed. The.relative lengths of the radii R and R and the locations of theircenters is such that the arcuate length of the convex part 4 is not lessthan twice as great as the arcuate length of the concave part 3. Itappears that the lines of freezing extending inwardly from thepredomiwell up into the ingot body, are so dispersed as to avoidinterference with other'lines of freezing 50 that such limited porousingot metal as is produced occurs only at or below the level of theconcave mold part 3 and the corresponding convex ingot part. However,the relation be- .tween the curvatures of the mold wall parts 3 andportions of the necked-in bottoms are now preferred, but the specificrelations may be varied in accordance with variations in mold and ingotsizes. Such variations may be made within the wall portion 4 intersectsbut is not tangent to the wall of the bottom opening 2. Such anarrangement, more fully described in my prior Patent 2,047,098,, isdesirable in order to avoid the formation of a protuberance extendingaround and just above the mold bottom opening and which would bevulnerable to the cutting action of the molten ingot metal when the moldis being teemed.

I Figure 4 shows an ingot I formed by casting in a mold of the kindshown in Figures 1, 2 and 3. Its surface contour is similar orcomplementary to the mold chamber wall contour and accordingly theseveral portions of the ingot surface are designated by primed numeralscorresponding to the unprimed numerals designating the respectivelycomplementary portions of the mold walls. Thus, the ingot side surfaceas a whole is designated l, the convex portion of the necked-in bottom Nis designated 3', and the concave portion of the necked-in bottom isdesignated d. The relative arcuate lengths of the portions 35 and t andthe relative lengths of their radii correspond respectively to therelative arcuate lengths and relative lengths of the radii of the moldwall portions 3 and 4.

As to molds and ingots of the size shown and described herein, thedisclosed relative curvatures and arcuate extents of the concave andconvex scope of the invention as defined in the claims.

I claim:

1. An ingot mold having a vertically-extending chamber defined by a wallwhich is neckedin at the bottom, the necked-in portion of the wallcomprising a concave part which merges with the mold wall proper and aconvex part connected to the concave part, the arcuate length of saidconvex part beingnot less than twice as great as the arcuate length ofsaid concave part.

2. An ingot mold having a vertically-extend ing chamber defined by awall which is necked in at the bottom, the necked-in portion of the'wallcomprising a concave part which merges with the mold wall proper and aconvex part connected to the concave part, said convex part being struckby a radius at least twice the length of the radius describing theconcave part, and the arcuate length of said convex part being not lessthan twice as great as the arcuate length of said concave part.

3. An ingot of big-end-up contour having a vertically extendin surfaceterminating at its lower portion in a concavo-convex contour, thearcuate length of the concave portion being not less than twice as greatas the arcuate length of said convex portion.

4. An ingot of blg-end-up contour having a vertically extending surfaceterminating at its lower portion in aconcavo-convex contour, the concaveportion being described by a radius at least twice the length ofthe-radius describing the convex portion, and the arcuate length of saidconcave portion being not less than twice as great as the arcuate lengthof said convex portion.

EMIL GATHMANN.

